Overhead conveyor

ABSTRACT

A conveyor having a main track and a local lower track and having double trolleys each being formed of a driving crab and a suspension crab. The suspension crab is detachably coupled to the driving crab by means of a self-centering ball and socket type coupling. In the coupled condition the suspension crab is locked against undesired uncoupling by safety means formed of a locking pawl pivotally arranged to engage various cam surfaces of the crabs in order to prevent undesired uncoupling.

- United States Patent 1 91 Velde [4 1 Apr. 3, 1973 [54] OVERHEADCONVEYOR 2,894,460 7/1959 Klamp ..104/83 Inventor: Harm Frank Te Velde,Eindhoven, 3,180,279 4/1965 Thlbault ..l04l89 Ne't'hcrlands PrimaryExaminer-Gerald M. Forlenza [73] Assxgnee: U.S. hi ip p n, New AssistantExaminer-Robert Saifer York, N.Y. Attorney-Eran]: R. Trifari [22] Filed:Jan. 5, 1971 [2]] Appl. No.: 104,069 [57] ABSTRACT A conveyor having amain track and a local lower [30] Foreign Application Priority Datatrack and having double trolleys each being formed of a driving crab anda suspension crab. The suspension Jan. 27, 1970 Netherlands ..7001084crab is detachably coupled to the driving crab y [52] U 8 Cl 104/172 8104/88 104/89 means of a self-centering ball and socket type 198/l77coupling. In the coupled condition the suspension crab 51 [111. CI 865g17/42 is against undesired uncmlpling by Safety 58 Field of Search..104/88 89 90 91 96 97 means firmed mung Pivmlly arranged 104/172 S 173178 lO'5/148 1 engage various cam surfaces of the crabs in order to 151,156; 168/177 R; 16/88; 24/324 prevent undesired uncoupling.

[ References Cited 16 Claims, 22 Drawing Figures UNITED STATES PATENTS2,632,402 3/1953 Reussner ..104 173 PATENTEDAPR 3 I975 SHEET UlUF 11IZ\"\ EN'1'OR.

HARM F. TE VELDE PATENTEDAPRB 975 3,724,391

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INVENTOR.

HARM F. TE VELDE w A FNT PATENTEU N I375 3,724,391

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AGE T PATENTEUAPR3 I975 SHEET 0 4 []F 11 Fig.3a

INVEN'I'OR.

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INVENTOR.

HARM F. TE VELDE m LWQ L- ANT PATENTEDAFM 1975 SHEET 07 0F 11 INVEN TORHARM F. TE VELDE PATENTEDAPR 3 I975 SHEET U80F 11 INVENTOR.

HARM F. TE VELDE PATENTEDAPR 3 I975 SHEET USUF 11 ENT PATH-HEB APR 31975 SHEET lUUF 11 PATENTEUAFR 3 I975 SHEET llflF 11 INVENTOR.

HARM E TE VELDE AGE T OVERHEAD CONVEYOR The invention relates to anoverhead conveyor having an endless transporting chain and a closedsingle guide track which together form a main track. At least one locallower track forming a side track is provided. Trolleys are provided,each consisting mainly of a driving crab and a suspension crab, thedriving crab travels in the guide track and may be driven by thetransporting chain and the suspension crab can be coupled to the drivingcrab by means of a detachable connection. The conveyor also has meansfor automatically coupling and uncoupling the suspension crabs andswitches for transferring the suspension crabs from one track to theother track.

Such a conveyor is already known. In this known device the detachableconnection consists of two hooks which are directed at right angles toeach other. The suspension crab is not safeguarded against a nondesiredand nonautomatic uncoupling, for example, as a result of irregularitiesduring conveying. Moreover, the said apparatus suffers from the drawbackthat the suspension crab can slide in an undesirable manner relative tothe driving crab, can rock about a horizontal axis, and can rotate abouta vertical axis.

It is the object of the invention to provide a conveyor which does notexhibit these drawbacks, in which the suspension crab is prevented fromundesirable and non-automatic uncoupling in all circumstances and alwaysassumes an accurately determined position relative to the driving crab.

The foregoing object is achieved by providing a detachable connectionwhich has a self-centering coupling and safety means, the connectionbeing adapted to be locked and unlocked automatically.

As a result of the self-centering coupling, the suspension crab isaccurately and automatically fixed relative to the driving crab;relative movements of the suspension crab and the driving crab areprevented in the coupled condition of the coupling. Due to the safetymeans and the automatic locking and unlocking of the connection,undesirable and non-automatic uncoupling of the suspension crab, otherthan in the switches, is not possible.

According to a preferred embodiment of the conveyor according to theinvention, the coupling consists of two cooperating spherical couplingmembers which are provided on two curved claws of the driving crab andthe suspension crab, which claws face each other and overlap each other,the safety means comprising a locking pawl on one claw and a locking camand a guide face on the other claw.

Due to the spherical coupling members, the suspension crab is capable ofpreforming all the necessary and desirable rotary movements relative tothe driving crab, in particular when the trolley travels along anincline. Coupling and uncouplingcan take place in a simple manner by acontrolled movement of the suspension crab in a vertical direction. As aresult of the claws which are curved and face each other, sufficientspace is available for said vertical movement. Rotary movement of thesuspension crab in the uncoupled lifted condition about a perpendicularaxis for transferring the suspension crab between the main track and theside track is thus possible. The locking pawl cooperating with thelocking cam prevents the undesired uncoupling of the suspension crab inone horizontal direction, the claw of the driving crab preventinguncoupling in the opposite direction.

A preferred embodiment of the conveyor according to the invention ischaracterized by cooperating stop surfaces on the two claws and on thelocking pawl. As a result of the stop surfaces contacting each other,displacements and rotary movements of the suspension crab relative to hedriving crab are restricted.

According to a further preferred embodiment of the conveying apparatusaccording to the invention, the claw of the driving crab is situatedpartly in the guide track, the free space between the guide track andthe spherical coupling member of said claw being smaller than thelifting stroke of the other coupling member necessary for uncoupling.

Due to the featured arrangement of the claw of the driving crab relativeto the guide track, the claw of the suspension crab in the uncoupledlifted condition becomes located partly between the guide track; theguide track prevents undesired lateral displacement and uncoupling, ifany, of the suspension crab.

As already explained, a rotary movement of the suspension crab in theuncoupled lifted condition and about a vertical axis is possible. Duringconveying, however, such a rotary movement of the suspension crab isusually not desired. In the coupled condition of the coupling, a rotarymovement of the suspension crab about a vertical axis and about ahorizontal axis parallel to the conveying apparatus is restricted, ifnecessary, by the coupling members being formed by a ball portion on theend of one one-armed claw and by a socket portion on the other two-armedclaw. The arms of the two-armed claw, in cooperation with the one-armedclaw, forms a guide for the suspension crab. The onearmed claw may beprovided on the driving crab and the ball portion points in thedirection of conveying, the two-armed claw forming part of thesuspension crab and having its socket portion remote from the directionof conveying. The locking pawl may be arranged on the one-armed claw soas to be rotatable and the locking cam with the guide face may bearranged on the two-armed claw.

As a result of this construction it is possible to arrange the lockingcam and the guide face on the upper side of the socket portion which hasa proportionally large area. In the coupled condition, the locking pawlbears on the guide face of the two-armed claw under the influence ofgravity, and thus assumes a favorable position for a succeeding renewedcoupling. In cooperation with the locking cam, the locking pawl preventsthe uncoupling of the suspension crab in the direction of conveying andin the uncoupled condition of the coupling. Further, the two clawsconstitute cooperating stop members in the case of any relative movementof the crabs in the opposite direction. In the uncoupled condition ofthe coupling, the two-arms claw with the socket portion is enclosedbetween the locking pawl, the one-armed claw and the guide track.

As already described above, the suspension crab in the coupled conditionis prevented from undesirable movements, both in the lateral directionand in the two longitudinal directions, and, if necessary, againstrotary movements about a perpendicular axis and about a horizontal axisparallel to the direction of conveying. However, rotary movements of thesuspension crab relative to the driving crab about a horizontal axisperpendicular to the direction of conveying must be possible in order tobe able to move along inclines during conveying. This can beaccomplished by having the locking pawl comprise a spherical supportingsurface the width of which is smaller than the free spacing between thearms of the two-armed claw, a locking projection and a recess betweenthe supporting surface and the locking projection.

The recess between the supporting surface and the locking projection ofthe locking pawl receives the locking cam, as a result of which rotarymovements of the crab about a horizontal axis perpendicular to theconveying apparatus and in both directions are possible without thefunction of the locking pawl being removed.

For transferring the suspension crabs from the main track to the sidetrack and from the latter back to the main track, the switches may beoperated manually. Preferably, however, the suspension crab comprises acoding beam with coding elements for the automatic control of theswitches.

The invention may be used, both in setting up new conveyors and inreconstructing existing conveyors. In both cases trolleys having thecharacteristic features according to the invention are used, each mainlyconsisting of a driving crab and a suspension crab, in which thesuspension crab can be coupled to the driving crab by means of adetachable connection and in which, according to the invention, thedetachable connection consists of a self-centering coupling and ofsafety means in which the connection can be automatically locked andunlocked.

In order that the invention may be readily carried into effect, oneembodiment thereof will now be described in greater detail, by way ofexample, with reference to the accompanying drawings, in which:

FIG. 1a shows a conveying diagram having a main track and a local lowertrack,

FIG. 1b diagrammatically shows the variation in height of the lowertrack,

FIG. 2a and 2b are a side view and a front elevation of a part of themain track of the conveyor according to the invention having a doubletrolley;

FIGS. 3a and 3b show the trolley during raising and lowering in the maintrack with an incline of 45,

FIGS. 4a and 4b are a side view and a front elevation of the main trackand of the local lower track with a trolley,

FIGS. 5a to 5d are sides view of the driving crab and the suspensioncrab in various positions during uncoupling,

FIGS. 6a to 6c are plan views of the driving crab and the suspensioncrab during transferring the suspension crab from the main track to theside track,

FIGS. 7a to 7c are plan views of the driving crab and the suspensioncrab during transferring the suspension crab from the side track back tothe main track,

FIGS. 80 to 8d are side views of the driving crab and the suspensioncrab during coupling.

FIG. la is a part of a conveying diagram showing a main track 1 and alocal lower track 3 which on the part A-C forms a double track with themain track 1 and the part C-D of which is constructed as an uncouplingswitch; the part D-E-F of the lower track 3 constitutes a loop-shapedside track 5 which, via a coupling switch F-G, again changes into adouble track G-K.

FIGS. 2a and 2b are a side view and a cross-sectional view,respectively, of a part of the main track 1, which is composed of anendless transporting chain 6 and of a hollow closed guide track 9 mainlyformed by four profile irons 7. The main track 1 serves to displace andguide double trolleys 11 one of which is shown in FIGS. 2 to 8. Eachtrolley 11 is mainly composed of a driving crab l3 and a suspension crab15 which is detachably coupled to the driving crab by means of aself-centering coupling 16. The driving crab 13 is driven bytransporting chain 6 travelling in the guide track 1; the profile irons7 of the hollow guide track 9 in cooperation with the supporting rollers17 and the guide rollers 19 of the driving crab l3 constitute a guidefor the trolley 1 1. For transferring the suspension crab 15 from themain track 1 to the side track 5, the suspension crab 15 may beuncoupled from the driving crab 13; during transferring of thesuspension crab 15 from the side track 5 to the main track 1, thesuspension crab 15 is again automatically coupled to the driving crabsl3 and in the coupled condition is absolutely prevented from anyundesirable uncoupling.

For that purpose, the driving crab 13 comprises a curved one-armed claw23 which is secured to links 21 between cross-pieces 22 of thetransporting chain 6 and which extends between the lower profile irons 7downwards and in the direction of conveying denoted by an arrow x. Thesuspension crab 15 also comprises a curved claw 25 the free end ofwhich, however, comprises two arms 27. This two-armed claw 25 extends ina direction opposite to the direction of conveying x, in such mannerthat the two claws 23 and 25 face each other and overlap each other. Aspherical coupling member which is formed of a ball portion 29 on thefree end of said claw is provided on the one-armed claw 23. Thetwo-armed claw 25 is provided with a corresponding spherical couplingmember which is formed of a socket portion 31 on the lower side of said'claw, the upper side 32 of which is flat. The claw 25 can be uncoupledby lifting the suspension crab 15. For coupling, the suspension crab 15is moved lowered, the socket portion 31 being automatically fixedrelative to the ball portion 29. In the coupled condition, the onearmedclaw 23 becomes situated partly between the arms 27 of the two-armedclaw 25. The free distance a between the lower side of the guide track 9and the ball portion 29 is smaller thanthe lifting stroke of the claw25. On the side of the driving crab l3 remote from the one-armed claw23, a locking pawl 23 is rotatably journalled on a shaft 34 in suchmanner that the free end thereof extends in the direction of thecoupling 16. The locking pawl 33 comprises a spherical supportingsurface 35, a locking projection 37, a recess 39 between the supportingsurface and the locking projection, and on either side, a stop surface40. The width of the supporting surface 35 and of the locking projection37 is smaller than the free distance b between'the arms 27 of the claw25. The socket portion 31 of the claw 25 comprises on its flat upperside 32 a locking cam 41 and a guide surface 43 which extendspartly'horizontally and partly at an angle. The cam and surface cancooperate with the locking projection 37 of the locking pawl 33.

The suspension crab comprises supporting rollers 45 and guide rollers47, a coding beam 49 with slidable coding pawls 51, a protection plate53 and a pivotable suspended hook 55 to which a product to be conveyedor a frame receiving a product can be secured.

FIGS. 2a and 2b show the trolley 11 with the driving crab 13 in theguide track 9 of the main track 1 during normal conveying, the coupledsuspension crab 15 being suspended from the driving crab 13. In thiscondition the claw 25 bears on the ball portion 29 of the claw 23 withits socket portion 31. The one-armed claw 23 extends partly between thearms 27 of the two armed-claw 25, the locking pawl 33 with the lockingprojection 37 resting on the guide surface 43. In this condition thesuspension crab 15 is fixed accurately relative to the driving crab 13by the self-centering coupling 16. If, as a result of irregularitiesduring conveying, the suspension crab 15 is lifted, the lockingprojection 37 is moved along the guide surface 43 in the direction ofthe locking cam 41, the locking pawl 33 performing a rotary movementabout the shaft 34. In extreme cases, the claws 23 and 25 may assume anuncoupled condition corresponding, for example, to FIG. 50. In spite ofthis, the suspension crab 15 is absolutely safeguarded againstuncoupling. Uncoupling of the suspension crab 15 in the direction ofconveying is prevented by the locking pawl 33 and in the oppositedirection by the ball portion 29 which forms a stop for the claw 25.Uncoupling of the suspension crab 15 in the lateral direction is alsoimpossible because the distance a between the lower side of the guidetrack 9 and the ball portion 29 is smaller than the lifting stroke ofthe claw 25 necessary for uncoupling. The result of this is that thearms 27 of the claw 25 in the lifted condition become situated betweenthe'lower profiled rods 7 of the guide track 9, as a result of which alateral uncoupling of the suspension crab is prevented.

The suspension crab 15 must be capable of performing rotary movementsabout a horizontal axis perpendicular to the direction of conveying, soas to be able to move along inclines in the main track 1 in bothdirections and with an unaltered vertical position of the crab 15. FIGS.3a and 3b show the trolley 11 during ascending and descending in anincline of 45 of the main track 1. In the position during ascendingshown in FIG. 3a, the socket portion 31 is rotated relative to the ballportion 29 in such manner that the locking pawl 33 becomes situated withits spherical supporting surface 35 between the two arms 27 of the claw25, the supporting surface 35 bearing on the ball portion 29. In thecase of a small perpendicular movement of the suspension crab 15 in thedirection of the guide track 9, the locking pawl 33 with its stopsurfaces 40 engages the upper side 32 of the claw 25 so that a furthermovement of said claw and the uncoupling of the suspension crab 15 isimpossible. The relative rotation of the crabs is restricted by stopsurfaces 30 and 44 on the claws which contact each other.

In the position shown in FIG. 3b during descending of the trolley 11,the socket portion 31 is rotated relative to the claw 23 in such mannerthat the locking pawl 33 bears with the locking projection 37 on theinclined part of the guide surface 43. In the case of a perpendicularmovement of the suspension crab 15 in the direction of the guide track9, the claw 25 with its surface32 contacts the stop surfaces 30 on theclaw 23 so that a further movement of the suspension crab 15 isprevented. In this position the rotary movement of the suspension crab15 is restricted in that it contacts with the inclined surface 48 thecross-piece 22 of the transporting chain 6. g

In every possible coupled condition of the trolley 11 in the main trackI, the arms 27 of the claw 25, in cooperation with the one-armed claw23, constitute a guide as a result of which undesirable rotary movementsof the suspension crab 15 about a perpendicular axis, as well as about ahorizontal axis parallel to the direction of conveying,,are restrictedto the necessary movements.

FIGS. 4a and 4b show the trolley 1 l in a double-track portion of themain track 1, with the driving crab 13 in the guide track 9, and withthe suspension c'rab 15 in the local lower track 3 which is constitutedby four profile irons 57. The profile irons 7 of the main track 1 andthe profile irons 57 of the lower track 3 may have the same dimensions.On this double-track portion of the main track 1 which is denoted by thepart A-B in FIGS. la and 1b which extends horizontally, the suspensioncrab 15 with the supporting rollers 45 contacts the profile irons 57, inwhich portion, however, the claws 23 and 25 are still in the coupledcondition. Moving the suspension crab 15 in the direction of the guidetrack 9 for uncoupling the claws is effected by means of the lower track3. The variation in the direction of height of the lower track 3 isshown in FIG. lb. On the part A-B the lower track 3 extendshorizontally. With automatic control of the uncoupling switch C-D,electronic, electro-optic or other automatically operating sensors areprovided for sensing the operative coding pawls on the coding beam 49for the automatic switching of the switch. of course the switch may alsobe operated manually. On the uncoupling part B C, the lower track 3extends upwards for uncoupling the claws 23 and 25. In the uncouplingswitch C-D, and in the coupling switch F-G, the suspension crabs 15 aredriven by switch wheels N and by pawls M which cooperate with recesses59 in the protecting plates 53 of the suspension crabs 15, the speeds ofthe pawls M and of the transporting chain 6 being synchronized. Themovement of the suspension crabs 15 in the side track 5 may take place,inter alia, by gravity, the lower track 3 being inclined downwards onthe part D-E-F. In the coupling switch F-G, the lower track 3 is alsohorizontal. 0n the coupling part G-I-l-K, the lower track 3 is inclinedupwards on the part G-I-l for raising the suspension crab 15. On thepart I-I-K the lower track 3 descends for lowering the suspension crab15 and for coupling the claws 23 and 25. I

FIGS. 5a to 5d are side views of various positions of the trolley 11during uncoupling the claws, the direction of conveying being denoted bythe arrow x. The main track 1 is shown only diagrammatically. On thehorizontal part A-B of the lower track 3, the claws are coupledtogether. This position for the point B of the track is shown in FIG.5a. When the suspension crab 15 moves upwards, which is effectedautomatically by the rising uncoupling part B-C of the lower track 3 asshown in FIG. 5b, the claw 25 is moved upwards over such a distance thatthe ball portion 29 is entirely released; figure 5c shows the claws 23and 25 in the uncoupled condition at the entrance C of the uncouplingswitch C-D, the suspension crab being still safeguarded. The suspensioncrab 15 is pushed by the driving crab 13, the ball portion 29 engagingthe inside 42 of the claw 25. Once the suspension crab 15 is removedfrom the main track 1, the locking pawl 33 will rest on the ball portion29 with its spherical supporting surface 35; the position of the lockingpawl 33 v is such that a renewed coupling and locking of the suspensioncrab 15 can take place automatically.

FIGS. 6a to 6c are plan views of various positions of the driving crab13 and the suspension crab 15 during transferring the suspension crabfrom the main track 1 to the side track 5 after uncoupling the claws.FIG. 6a which corresponds to FIG. 50 shows the claws 23 and 25 in theuncoupled condition at the entrance C of the uncoupling switch C-D. Theuncoupling switch is already in the desired position for transferringthe suspension crab 15. By a rotary movement of the suspension crababout a perpendicular axis and in the uncoupling switch, the suspensioncrab is removed from the main track land follows the lower track 3 whichchanges into the side track 5, while the driving crab ,13 remainsfollowing the main track 1. FIGS. 6b and 60 show relative positions ofthe driving crab 13 and of the suspension crab 15 during uncoupling andtransfer of the suspension crab 15. I

FIGS. 7a to 70 show a few positions of the driving crab 13- and of thesuspension crab 15 during the transfer thereof from the side track 5back to the main track 1. FIG. 7a shows the positions of the drivingcrab l3 and of the suspension crab 15 before the exit G of thehorizontally extending coupling switch F-G. At point G of the switchsuspension crab 15 is transferred in the main track 1 by thesynchronized drive of the pawls M in such manner that the claw 23engages the arms 27 of the claw 25 with its ball portion 29. In thisposition, which is shown in FIG. 7b, the suspension crab I5 is pushed bythe driving crab 13. FIG. 8b is a side elevation of the driving crab l3and the suspension crab 15 in a position corresponding to FIG. 7b. Onthe adjoining ascending part G-I-I of the lower track 3 the suspensioncrab 15 is moved upwards, during which the ball portion 29 can slidealong the bevelled lower sides of the arms 27 of the claw 25 and engagesthe inner edge 42 of said claw. FIGS. 70 and 8c show the claws 23 and 25on the ascending part G-I-I in a position in which they are not yetcoupled, the suspension crab being already safeguarded from undesirablecoupling.

Adjoining the ascending action of the suspension crab 15, it is againlowered on the descending part I-I-K of the lower track 3. FIG. 8d showsthe claws 23 and 25 on the descending part I-l-K during coupling.

As already described in detail, the suspension crab is absolutelysafeguarded by the locking pawl 33 in every possible coupled conditionof the claws both on the horizontal and on the ascending and descendingparts. In the uncoupled conditions of the claws in the doubletrack ofthe main track, before the uncoupling switch and behind the couplingswitch, the uncoupling of the suspension crab both in the twolongitudinal directions and in the lateral direction is also impossible.Moreover, the suspension crab 15 in the double-track part is guided inthe lower track 3.

By the self-centering action of the coupling the suspension crab 15 isautomatically and accurately placed relative to the driving crab 13, aproportionally large relative rotary movement of the driving crab l3 andthe suspension crab 15 about a horizontal axis perpendicular to thedirection of conveying in both directions being possible. The locking ofthe suspension crab is effected automatically and in a simple manner bythe locking pawl 33, by the claws 23, 25 and by the various stopsurfaces; undesirable uncoupling other than in the switches is notpossible. If intentional manual unlocking is desired, it is necessaryonly to lift the locking pawl 33 and to remove the suspension crab 15with the claw 25 from the driving crab 13.

The invention has been described with referenceto an embodiment having asingle trolley. Of course, all the trolleys of the conveying apparatusare coupled and uncoupled in the manner described, it being possible tocombine any suspension crab with any driving crab.

The embodiment described and shown in the drawing is a preferredembodiment of the conveyor according to the invention. The inventionalso comprises embodiments in which the shape and the relativearrangement of the claws, of the spherical coupling members, and of thelocking pawl deviate from the embodiment.

What is claimed is:

1. An overhead conveyor having an endless transporting chain and aclosed single guide track which together form a main track, at least onelocal lower track forming a side track, a plurality of trolleys eachcomprising a driving crab and a suspension crab, said driving crabtravelling in the guide track so as to be driven by the transportingchain, a detachable connection for coupling the suspension crab to thedriving crab, means for automatically coupling and uncoupling thesuspension crabs, switches for transferring the suspension crabs fromone track to the other track, said detachable connection comprising aself-centering coupling and safety means, the connection being adaptedto be locked and unlocked automatically, said coupling comprising twocooperating spherical coupling members which are provided on curvedclaws one of which is provided on the driving crab and the other ofwhich is provided on the suspension crab, which claws face each otherand overlap each other, the safety means comprising a locking pawl onone claw and locking cam and guide face on the other claw.

2. A conveyor as claimed in claim 1, further comprising cooperating stopsurfaces on the two claws and on the locking pawl.

3. A conveyor as claimed in claim 1 wherein the claw of the driving crabis situated partly in the guide track, the free distance between theguide track and the spherical coupling member of said claw being smallerthan the uncoupling stroke of the other coupling 5. A conveyor asclaimed in claim 4, wherein the ball portion is mounted on the one-armclaw which extends in the direction of conveying, and said socketportion is mounted on the two-armed claw of said suspension crab whichextends in the direction opposite to that of conveying, said lockingpawl being arranged on the one-armed claw so as to be rotatable and thelocking cam with the guide face being arranged on the twoarmed claw.

6. A conveyor as claimed in claim 5, wherein the locking pawl comprisesa spherical supporting surface the width of which is smaller than thefree distance between the arms of the two-armed claw, a lockingprojection and a recess between the supporting surface and the lockingprojection.

7. A conveyor as claimed in claim 1, further comprising a coding beamwith coding elements for the automatic control of the switches on saidsuspension crab.

8. An overhead conveyor having a closed guide track, a transportingchain carried in said guide track, and a side track, at least onetrolley arranged for transport in said tracks comprising a driving craband a suspension crab, said driving crab being guided in said guidetrack and driven by said transporting chain, a curved claw provided onsaid driving crab and on said suspension crab, a detachable connectionfor coupling said suspension crab to said driving crab comprising aself-centering coupling between said driving and suspension crabs formedby spherically shaped coupling members carried by said curved claws,said claws arranged to face and overlap each other so that thespherically shaped members will cooperatively engage each other toeffect coupling, safety means carried on said claws for preventingunintentional uncoupling, means for automatically coupling anduncoupling said crabs, and switch means for transferring the suspensioncrabs from one track to the other.

9. The overhead conveyor according to claim 8, wherein said safety meanscomprises a locking pawl mounted for pivotal movement on one of saidclaws and a locking cam and guide face mounted on the other of saidclaws.

10. The overhead conveyor according to claim 9, further comprisingcooperating stop surfaces on said claws and on the locking pawl.

11. The overhead conveyor according to claim 8 wherein said curved clawof said driving crab is arranged within said guide track, the distancebetween the guide track and said spherically shaped coupling member onthe curved claw of said driving crab being smaller than the strokerequired for uncoupling the suspension crab from the driving crab.

12. The overhead conveyor according to claim 8 wherein the curved clawof said driving crab is onearmed claw and wherein the curved claw ofsaid suspension crab is a two-armed claw, said spherically shapedcoupling members comprising a ball portion carried on the end of saidone-armed claw and a socket portion formed on the two armed claw incooperation with the one-armed claw forming a guide for the suspensioncrab.

13. The overhead conveyor according to claim 12 wherein said one-armedclaw extends in a direction of conveyance of said trolley and whereinsaid two-armed claw extends in a direction opposite to the direction ofconveging.

14. he overhead conveyor according to claim 13, wherein said lockingpawl is mounted for pivotal movement on said one-armed claw and saidlocking cam and guide surface is arranged on said two-armed claw.

15. The overhead conveyor according to claim 14, wherein said lockingpawl comprises a spherical supporting surface the width of which issmaller than the distance between the arms of said two-armed claw, andfurther comprising a locking projection and a recess between thesupporting surface and the locking projection.

16. The overhead conveyor according to claim 8, further comprising acoding beam with coding elements for automatic control of the switchesconnected to said suspension crab.

1. An overhead conveyor having an endless transporting chain and aclosed single guide track which together form a main track, at least onelocal lower track forming a side track, a plurality of trolleys eachcomprising a driving crab and a suspension crab, said driving crabtravelling in the guide track so as to be driven by the transportingchain, a detachable connection for coupling the suspension crab to thedriving crab, means for automatically coupling and uncoupling thesuspension crabs, switches for transferring the suspension crabs fromone track to the other track, said detachable connection comprising aselfcentering coupling and safety means, the connection being adapted tobe locked and unlocked automatically, said coupling comprising twocooperating spherical coupling members which are provided on curvedclaws one of which is provided on the driving crab and the other ofwhich is provided on the suspension crab, which claws face each otherand overlap each other, the safety means comprising a locking pawl onone claw and locking cam and guide face on the other claw.
 2. A conveyoras claimed in claim 1, further comprising cooperating stop surfaces onthe two claws and on the locking pawl.
 3. A conveyor as claimed in claim1 wherein the claw of the driving crab is situated partly in the guidetrack, the free distance between the guide track and the sphericalcoupling member of said claw being smaller than the uncoupling stroke ofthe other coupling member necessary for uncoupling.
 4. A conveyor asclaimed in claim 1, whereIn the driving crab has a one-armed claw andthe suspension crab has a two-armed claw, and wherein said couplingmembers comprise a ball portion on the end of said one-armed claw and bya socket portion on the two-armed claw, the arms of the two-armed claw,in cooperation with the one-armed claw, forming a guide for thesuspension crab.
 5. A conveyor as claimed in claim 4, wherein the ballportion is mounted on the one-arm claw which extends in the direction ofconveying, and said socket portion is mounted on the two-armed claw ofsaid suspension crab which extends in the direction opposite to that ofconveying, said locking pawl being arranged on the one-armed claw so asto be rotatable and the locking cam with the guide face being arrangedon the two-armed claw.
 6. A conveyor as claimed in claim 5, wherein thelocking pawl comprises a spherical supporting surface the width of whichis smaller than the free distance between the arms of the two-armedclaw, a locking projection and a recess between the supporting surfaceand the locking projection.
 7. A conveyor as claimed in claim 1, furthercomprising a coding beam with coding elements for the automatic controlof the switches on said suspension crab.
 8. An overhead conveyor havinga closed guide track, a transporting chain carried in said guide track,and a side track, at least one trolley arranged for transport in saidtracks comprising a driving crab and a suspension crab, said drivingcrab being guided in said guide track and driven by said transportingchain, a curved claw provided on said driving crab and on saidsuspension crab, a detachable connection for coupling said suspensioncrab to said driving crab comprising a self-centering coupling betweensaid driving and suspension crabs formed by spherically shaped couplingmembers carried by said curved claws, said claws arranged to face andoverlap each other so that the spherically shaped members willcooperatively engage each other to effect coupling, safety means carriedon said claws for preventing unintentional uncoupling, means forautomatically coupling and uncoupling said crabs, and switch means fortransferring the suspension crabs from one track to the other.
 9. Theoverhead conveyor according to claim 8, wherein said safety meanscomprises a locking pawl mounted for pivotal movement on one of saidclaws and a locking cam and guide face mounted on the other of saidclaws.
 10. The overhead conveyor according to claim 9, furthercomprising cooperating stop surfaces on said claws and on the lockingpawl.
 11. The overhead conveyor according to claim 8 wherein said curvedclaw of said driving crab is arranged within said guide track, thedistance between the guide track and said spherically shaped couplingmember on the curved claw of said driving crab being smaller than thestroke required for uncoupling the suspension crab from the drivingcrab.
 12. The overhead conveyor according to claim 8 wherein the curvedclaw of said driving crab is one-armed claw and wherein the curved clawof said suspension crab is a two-armed claw, said spherically shapedcoupling members comprising a ball portion carried on the end of saidone-armed claw and a socket portion formed on the two armed claw incooperation with the one-armed claw forming a guide for the suspensioncrab.
 13. The overhead conveyor according to claim 12 wherein saidone-armed claw extends in a direction of conveyance of said trolley andwherein said two-armed claw extends in a direction opposite to thedirection of conveying.
 14. The overhead conveyor according to claim 13,wherein said locking pawl is mounted for pivotal movement on saidone-armed claw and said locking cam and guide surface is arranged onsaid two-armed claw.
 15. The overhead conveyor according to claim 14,wherein said locking pawl comprises a spherical supporting surface thewidth of which is smaller than the distance between the arms of saidtwo-armed claw, and further comprising a locking projection and A recessbetween the supporting surface and the locking projection.
 16. Theoverhead conveyor according to claim 8, further comprising a coding beamwith coding elements for automatic control of the switches connected tosaid suspension crab.